显微组织对医用TC4钛合金U型钉缩口的影响

Effect of Microstructure on Necking of Medical U-shaped Nail of TC4 Titanium Alloy

通过光学显微镜、维氏硬度、拉伸实验、X射线衍射和电子背散射衍射等方法,对比分析了两种缩口尺寸不同的医用U型钉用TC4钛合金棒材的显微组织和力学性能。基于两种棒材的显微组织和力学性能的差别,探讨了不同棒材加工的U型钉缩口差异的原因。结果表明:两种棒材横截面的显微组织比较均匀,差异不大,而纵截面显微组织的差异比较明显。大缩口棒材纵截面的α相为变形晶粒,小缩口棒材纵截面的β相主要为等轴晶,两种棒材的β相无明显差别。大缩口棒材的维氏硬度和屈服强度都高于小缩口棒材。再结晶程度的不同导致两种棒材的显微组织和力学性能不同,进而引起U型钉缩口的差异。

Microstructure and mechanical properties of two medical TC4 titanium alloy bars, which made medical U-shaped nails with different necking size, were studied by optical microscope, Vickers hardness, tensile test, X-ray diffraction （XRD） and electron backscatter diffraction （EBSD）. Based on the difference of microstructure and mechanical properties of two TC4 alloy bars, the reason why necking of U-shaped nails didn＇t unit had been explored. The results show that microstructure of two TC4 alloy bars are uniform at the cross-section, However, α phase of big necking bar is mainly deformed grain at the longitudinal-section, while the small necking bar is mainly equiaxial grain. In addition, β phase of two bars has no obvious difference. The Vickers hardness and yield strength of big necking bar are higher than that of small necking bar. The different degree of recrystallization of two bars contributes to the different mierostructure and mechanical properties,which results in the difference of necking size of U-shaped nails.